Principal goals for cartons or containers used in the fast food industry wherein only a single use is contemplated include the formation of cartons to both properly and safely accommodate the foodstuffs, and to in themselves be an economical and practical product.
The carton, when open, must allow for quick and easy introduction of the food product. The carton must also be able to both close and lock in a positive manner, and easily open for access to the carton contents. Another desirable feature, particularly in preassembled fast food cartons folded from blanks of paperboard or the like, is the capability for a compact nesting of the cartons for storage and shipment. As an example of cartons incorporating the above features, attention is directed to applicant's prior U.S. Pat. No. 4,877,178, issued Oct. 31, 1989.
While cartons for fast food and the like are provided in a variety of sizes to generally correspond with the foodstuffs to be received therein, such cartons are, as in the above patent, conventionally of rectangular configuration and without regard to the specific shape of the goods to be received. For example, notwithstanding that the conventional pizza is circular, the conventional pizza box is square. In such situations, there is wasted space within the carton and the use of excess paperboard in the formation of the "oversized" carton.
The parent applications teach the provision of cartons which are configured for the specific accommodation of the conventional round pizza or similarly shaped food item. The prior cartons, utilizing straight sides for convenience in forming, are provided with a number of sides, more than four and preferably six, to approach a circular configuration, thus minimizing excess interior space and reducing the amount of material utilized while at the same time providing the basic simplicity and economical construction of a conventional rectangular "hamburger" carton.
In view of the multiple sides provided on the preferred hexagonal carton, there is a tendency when handling the full carton in one hand to grasp the box at any point about the periphery. This, in view of the internal weight of the pizza and the rather flexible nature of the carton, tends to cause a slight flexing or distortion of the loaded carton as might tend to at least partially disengage the cover from the tray. As such, and in view of the relatively large surface area of a pizza box as compared to a much smaller hamburger box, it is particularly important that a positive interlock be provided between the tray and the cover closed thereon. The provision of a positive and effective locking arrangement between the tray and cover has been a goal of applicant's previous efforts.